CommandShell 4.2.1 is a substantial rewrite of CommandShell 3. It uses event driven IO when the AioPlugin is available; otherwise it relies on polling loops similar to CommandShell 3. Shell syntax is now separated from the CommandShell, and different views permit graphical windows based on Transcript (Morphic and MVC), or an external teletype style view for interacting with a headless Squeak from a command line.
CommandShell 4.2.1 works with GraphViz, but has not been tested with any other packages that may depend on it.
OSProcess version 4.3.5 or greater is recommended, as a concurrency bug has been addressed that previously caused intermittent failures in the CommandShell test suite. If AioPlugin is used, version 2.2 or greater is recommended. Earlier versions had a bug that limited the number of file handles to 19, causing intermittent problems in the CommandShell test suite. Note that AioPlugin may not be included with your VM, even if OSProcessPlugin is present. VM builders may find AioPlugin, OSProcessPlugin, and XDisplayControlPlugin on SqueakMap, SqueakSource, and on the swiki.
The MVC environment is broken on some Squeak images (notably Squeak 3.10), so CommandShell does not work under MVC in those images.